This invention relates generally to air conditioning systems and, more particularly, to a condensate disposal system for a packaged terminal air conditioner.
Warm air is also frequently humid, i.e. it contains entrained water vapor. During operation of an air conditioning system in the cooling mode, the system refrigerant evaporator reduces the temperature of the air to a level below its dew point. In that condition, water vapor condenses on the evaporator. Some means must be provided to dispose of this condensate. In small unitary air conditioners, such as window or through-the-wall mounted room air conditioners, a common means to accomplish condensate disposal is by providing a condensate collection and drain path that communicates between the indoor and outdoor sections of the air conditioner. Condensate formed on the system evaporator drains into a collector in the indoor section and then flows to a location under or near the condenser fan in the outdoor section. A condensate distribution device is then provided to pick up the condensate and cause it to flow onto the hot surfaces of the system condenser where the condensate water evaporates. Such an arrangement eliminates the need for an inconvenient, unsightly and costly condensate drain from the air conditioner. Further, it provides for an economical use of the condensate in that the heat necessary to evaporate the water is taken from, and thus assists in the cooling of, the warm refrigerant in the condenser, thus resulting in an improvement in system efficiency.
Common condensate distribution schemes include vortex impellers or aspirators, slinger rings, mechanical pumps or specially designed fan blade tips. In window room air conditioners and packaged terminal air conditioners, it is most common to use a slinger arrangement associated with a condenser fan. In a typical slinger arrangement, a blow-through propeller fan coil configuration is used and the condensate collects at a location where the fan structure causes the condensate to be splashed onto the condenser coil, where it is evaporated, thereby providing cooling to the condenser.
The effectiveness of such a condensate disposal system, i.e. wherein a propeller fan is used to distribute the cold condensate generated by the indoor coil to be evaporated on the hot outdoor coil, is dependent on the following factors: (a) the distribution area of condensate onto the outdoor coil surface; (b) the temperature of that condensate spray; (c) the volume of condensate distributed to the coil and; (d) the amount of condensate that is held in the sump.
Typically the sump, where the water is collected from below the evaporator coil and flows to the condenser side for distribution, comprises a relatively large, flat pan which requires the accumulation of a considerable amount of condensate in order to rise to the level where it can be distributed onto the condenser coil. Thus, there can be standing water (i.e. as much as 1-1.5 gallons) in the sump, with no distribution taking place. Not only does this cause a delay of time until efficient operation occurs, but it also causes an undesirable condition of having stagnant water in the sump, which could cause the growth of fungus, legionnaire's disease, and the like. Further, because of the need for substantial accumulation, the temperature of the water when it finally reaches the distribution system is substantially warmer than the temperature of the condensate coming off the evaporator coil, thereby lowering the efficiency of the unit.
Generally, the condensate distribution approaches that have been used, tend to provide a relatively poor distribution of condensate across the face of the condenser coil. For example, the slinger ring tends to lift the condensate and have it blown by the fan blades into the condenser coil in a relatively small concentrated area rather than over the entire face of the condenser coil. Further, not all of the water lifted from the condensate collector is carried into the fan discharge. Some, in the form of droplets, is thrown radially outward until it impacts the system enclosure or other structural components, particularly when the fan is operating at a higher speed. Shrouds may be used to direct the droplets onto the condenser rather than on the surrounding system structures, but these structures add expense and complication.
Finally, since the full benefit of the use of the condensate to cool the condenser coil is not gained for the reasons discussed hereinabove, the condensing temperature is not lowered as much as would otherwise occur, thereby resulting in a higher evaporator temperature and less condensate being formed. The efficiency of the system is accordingly reduced.
It is therefore an object of the present invention to provide an improved condensate disposal system for an air conditioning system.
Another object of the present invention is the provision in a condensate disposal system for the improved distribution of water onto the condenser coil surface.
Yet another object of the present invention is the provision in a condensate disposal system for lowering the temperature of the water being sprayed onto the coil.
Still another object of the present invention is the provision in a condensate disposal system for increasing the volume of condensate being distributed to the coil.
Yet another object of the present invention is the provision in a condensate disposal system for reducing the amount of condensate that is held in the sump of an air conditioner.
These objects and advantages become more readily apparent on reference to the following description when taken in conjunction with the appended drawings.